#pragma once


#include <iostream>
#include <string>
#include <vector>
#include <mutex>
#include <cassert>
#include <algorithm>
#include <fstream>
#include <jsoncpp/json/json.h>

#include "../comm/util.hpp"
#include "../comm/log.hpp"
#include "../comm/httplib.h"
// #include "oj_model1.hpp"
#include "oj_model2.hpp"
#include "oj_view.hpp"


namespace ns_control
{
    using namespace std;
    using namespace ns_log;
    using namespace ns_util;
    using namespace ns_model2;
    using namespace ns_view;
    using namespace httplib;

    
    //提供服务的主机
    class Machine
    {
    public:
        std::string ip; //编译服务的ip
        int port;       //编译服务的port
        uint64_t load;  //编译服务的负载  -> 负载的增加一定是原子的(引入锁)
        std::mutex* mtx;//mutex是禁止拷贝的,所以用指针来完成
    public:
        Machine():ip(""),port(0),load(0),mtx(nullptr)
        {}
        ~Machine()
        {}
        //提升主机负载
        void IncLoad()
        {
            if(mtx)
            {
                mtx->lock();
            }
            load++;
            if(mtx)
            {
                mtx->unlock();
            }
        }
        //减少主机负载
        void DecLoad()
        {
            if(mtx)
            {
                mtx->lock();
            }
            load--;
            if(mtx)
            {
                mtx->unlock();
            }
        }
        void ResetLoad()
        {
            if(mtx)
            {
                mtx->lock();
            }
            load = 0;
            if(mtx)
            {
                mtx->unlock();
            }
        }
        //获取主机负载
        uint64_t Load()
        {
            uint64_t _load = 0;
            if(mtx)
            {
                mtx->lock();
            }
            _load = load;
            if(mtx)
            {
                mtx->unlock();
            }
            return _load;
        }
    };

    const std::string service_machine = "./conf/service_machine.conf";
    //负载均衡模块
    class LoadBlance
    {
    private:
        //可以给我们提供编译服务的机器
        //每一台主机都有自己的下标,充当当前主机的id
        std::vector<Machine>  machines;
        //所以在线主机的id
        std::vector<int> online;
        //所以离线主机的id
        std::vector<int> offline;
        //保证LoadBlance它的数据安全
        std::mutex mtx;
    public:
        LoadBlance()
        {
            assert(LoadConf(service_machine));
            LOG(INFO) << "加载 " << service_machine << " 成功" << "\n";
        }
        ~LoadBlance()
        {

        }
    public:
        bool LoadConf(const std::string& machine_conf)
        {
            std::ifstream in(machine_conf);
            if(!in.is_open())
            {
                LOG(FATAL) << " 加载: " << machine_conf << "失败" << "\n";
                return false;
            }
            std::string line;
            while(std::getline(in,line))
            {
                std::vector<std::string> tokens;
                StringUtil::SplitString(line,&tokens,":");
                if(tokens.size() != 2)
                {
                    LOG(WARNING) << " 切分 " << line << "失败" << "\n";
                    continue;
                }
                Machine m;
                m.ip = tokens[0];
                m.port = atoi(tokens[1].c_str());
                m.load = 0;
                m.mtx = new std::mutex();
                online.push_back(machines.size());
                machines.push_back(m);
            }
            in.close();
            return true;
        }
        //id: 输出型参数
        //m : 输出型参数
        bool SmartChoice(int* id,Machine** m)
        {
            //1. 使用选择好的主机(更新该主机的负载)
            //2. 我们需要可能离线该主机
            mtx.lock();
            // 负载均衡的算法
            // 1. 随机数法+hash
            // 2. 轮询 + hash
            int online_num = online.size();
            if(online_num == 0)
            {
                mtx.unlock();
                LOG(FATAL) << "所有的后端编译主机已经离线" << "\n";
                return false;
            }
            //遍历的方式找到负载最小的机器
            *id = online[0];
            *m = &machines[online[0]];
            uint64_t min_load = machines[online[0]].Load();
            for(int i=1;i<online_num;i++)
            {
                uint64_t curr_load = machines[online[i]].Load();
                if(min_load > curr_load)
                {
                    min_load = curr_load;
                    *id = online[i];
                    *m = &machines[online[i]];
                }
            }
            mtx.unlock();
            return true;
        }
        void OfflineMachine(int id)
        {
            mtx.lock();
            for(auto iter = online.begin();iter != online.end();iter++)
            {
                if(*iter == id)
                {
                    machines[id].ResetLoad();
                    //要离线的主机
                    online.erase(iter);
                    offline.push_back(id);
                    break;//不考虑迭代器失效问题
                }
            }
            mtx.unlock();
        }
        void OnlineMachine()
        {
            //当所有主机都离线的时候,我们统一上线
            mtx.lock();
            online.insert(online.end(),offline.begin(),offline.end());
            offline.erase(offline.begin(),offline.end());
            mtx.unlock();
            LOG(INFO) << "所有的主机又上线了" << "\n";
        }

        //for test
        void ShowMachines()
        {
            mtx.lock();
            std::cout << "当前在线主机列表:";
            for(auto& id:online)
            {
                std::cout << id << " ";
            }
            std::cout << std::endl;

            std::cout << "当前离线主机列表:";
            for(auto& id:offline)
            {
                std::cout << id << " ";
            }
            std::cout << std::endl;
            mtx.unlock();
        }
    };

    //这是我们核心业务逻辑的控制器
    class Control
    {
    private:
        Model model_; //提供后台数据
        View view_;   //提供html渲染功能
        LoadBlance load_blance_;//核心负载均衡器
    public:
        Control()
        {
            
        }

        ~Control()
        {

        }
        void RecoveryMachine()
        {
            load_blance_.OnlineMachine();
        }

        //根据题目数据构建网页
        bool AllQuestions(std::string *html)
        {
            bool ret = true;
            vector<Question> all;
            if(model_.GetAllQUestions(&all))
            {
                //获取一个题目信息成功,将所有的题目数据构建成网页
                //题目进行排序
                sort(all.begin(),all.end(),[](const Question& q1,const Question& q2){
                    return atoi(q1.number.c_str()) < atoi(q2.number.c_str());
                });
                view_.AllExpandHtml(all,html);
            }
            else
            {
                *html = "获取题目失败,形成题目列表失败";
                ret = false;
            }
            return ret;
        }

        bool OneQuestion(const string& number,string* html)
        {
            bool ret = true;
            Question q;
            if(model_.GetOneQUestion(number,&q))
            {
                //获取指定题目信息成功,将所有的题目数据构建成网页
                view_.OneExpandHtml(q,html);
            }
            else
            {
                *html = "指定题目: " + number + " 不存在!";
                ret = false;
            }
            return ret;
        }

        /******************************************************
        * in_json:
        * code : #include...
        * input : ""
        ******************************************************/
        void Judge(const std::string& number,const std::string in_json,std::string *out_json)
        {
            //0.根据题目编号,直接拿到对应的题目细节
            Question q;
            model_.GetOneQUestion(number,&q);
            //1. in_json进行反序列化,得到题目id,得到用户提交源代码,input
            Json::Reader reader;
            Json::Value in_value;
            //反序列化
            reader.parse(in_json,in_value);
            std::string code = in_value["code"].asString();
            //2. 重新拼接用户代码和测试用例代码
            Json::Value compile_value;
            compile_value["input"] = in_value["input"].asString();
            compile_value["code"] = code + "\n" + q.tail;
            compile_value["cpu_limit"] = q.cpu_limit;
            compile_value["mem_limit"] = q.mem_limit;
            //Json写入器
            Json::FastWriter writer;
            //序列化
            std::string compile_string = writer.write(compile_value);
            //3. 选择负载最低的主机(差错处理)
            //规则:一直选择,直到主机可用,否则,就是全部挂掉
            while(true)
            {
                int id = 0;
                Machine* m = nullptr;
                if(!load_blance_.SmartChoice(&id,&m))
                {
                    break;
                }
                
                //4. 发起请求,得到结果
                Client cli(m->ip,m->port);
                m->IncLoad();
                LOG(INFO) << " 选择主机成功,主机id: " << id << " 详情: " << m->ip << ":" <<m->port << " 当前主机的负载是: " << m->Load() <<"\n";

                if(auto res = cli.Post("/compile_and_run",compile_string,"application/json;charset=utf-8"))
                {
                    //5. 将结果赋值给out_json
                    if(res->status == 200)
                    {
                        *out_json = res->body;
                        m->DecLoad();
                        LOG(INFO) << "请求编译和运行服务成功... " << "\n";
                        break;
                    }
                    m->DecLoad();
                }
                else
                {
                    //请求失败
                    LOG(ERROR) << " 当前请求的主机id: " << id << " 详情: " << m->ip << ":" <<m->port << "可能已经离线" << "\n";
                    load_blance_.OfflineMachine(id);
                    load_blance_.ShowMachines();
                }
            }
        }
    };
}






